Select the most appropriate option that can substitute the highlighted segment in the given sentence.
Research in Social Sciences is plagued nowadays on gloomy definitions and measurements.

Correct option is B

The correct substitution of the highlighted words is (b) nowadays by gloomy definitions.
Explanation:
“Plagued” is usually followed by the preposition “by” to indicate the cause of distress or trouble. “Plagued by” means affected by something undesirable.
So, "plagued nowadays by gloomy definitions" is the correct phrase.
Grammatical rule used:
Verbs like "plagued", "affected", "haunted", etc. take "by" for indicating cause.
Example: The country was plagued by inflation.
Information Booster: Prepositions often follow specific verbs. Always verify collocations like “plagued by”, “affected by”, “worried about” etc.